1. Field of the Invention
The present invention relates to a paper feeding apparatus, and more particularly, to a paper feeding apparatus for use in an image forming apparatus, which advantageously utilizes a single driving source to drive both a knock-up plate and a paper feeding roller assembly at the same time.
2. Related Art
Generally, a paper feeding apparatus is included as part of an image forming apparatus, such as a printer, a facsimile machine, a photocopier and a multi-functional product, for feeding individual sheets of print media such as papers into the image forming apparatus. As shown in FIG. 1, a typical multi-functional product 100 comprises an image former 110 to form an image on a paper 1; an image reader 120 coupled to an upper part of the image former 110 to read documents and transfer image data to the image former 110; and a paper feeding apparatus 130 provided on a lower part of the image former 110 to feed individual sheets of paper 1 from a paper feeding cassette 140 to the image former 110. The image reader 120 includes an image reading table 122, typically of a flatbed type, to accommodate different standard sized papers, and an automatic document feeder (ADF) 124 to automatically feed individual sheets of paper to be read to the image reader 120. In addition, a housing 101 is provided to house the image former 110, the paper feeding apparatus 130, the paper feeding cassette 140 and related components, along with a control panel 103 provided with a controller (not shown) for controlling operation of the image former 110, the image reader 120, the paper feeding apparatus 130 and other components, as well as a display panel 105 for providing visual display of operation. Each paper 1 which is stacked on a knock-up plate 131 of the paper feeding apparatus 130 is picked up by a pick-up roller 201 to be supplied to a paper feeding roller 202. Meanwhile, a reverse roller 204 rotates corresponding to the paper feeding roller 202, and enables the paper 1 to be supplied as a single sheet to the image former 110. The paper 1 which passes through the paper feeding roller 202 and the reverse roller 204 is conveyed by conveying rollers 142 and has an image transferred onto it by a photosensitive drum 111 and a transfer roller 112 of the image former 110. Then, the transferred image is fused on the paper by fixing rollers 113. After fusing, the paper 1 is ejected to the outside through an outlet 114. The image former 110 is positioned inside the housing 101, whereas the paper feeding cassette 140 is removable from the housing 101.
FIG. 2 is a schematic view illustrating a driving relation of a paper feeding apparatus 130 used in the multi-functional product shown in FIG. 1. A driving source of the paper feeding apparatus 130 comprises a main driving motor 210 for driving a pick-up roller 201, a paper feeding roller 202 and a reverse roller 204; and a lift motor 220 for driving a lift gear 221, a partial gear 222 and a lift bar 223 to rotate upwardly the knock-up plate 131 for picking up individual sheet of paper 1 to be fed into the image former 110 for image formation. The main driving motor 210 drives the paper feeding roller 202 and the reverse roller 204 through a plurality of gears 211 and a pick-up clutch 212, and drives the pick-up roller 201 through a transmission gear 206. The lift motor 220 rotates a partial gear 222 through a lift gear 221 such that the partial gear 222 can rotate a lift bar 223 fixed with the same shaft, so as to enable the knock-up plate 131 to rotate upwardly.
The knock-up plate 131, the pick-up roller 201, the partial gear 222 and the lift bar 223 of the paper feeding apparatus 130 in FIG. 1 are mounted to the paper feeding cassette 140. A paper feeding gear 203 and a reverse gear 205 are fixed on the same shaft as the paper feeding roller 202 and the reverse roller 204, respectively to enable individual sheet of paper 1 to be fed into the image former 110 for image formation.
As shown in FIG. 2, the paper feeding apparatus 130 requires separate and independent driving sources to feed individual sheet of paper 1 into the image former 110. Specifically, the paper feed apparatus 130 requires a main driving motor 210 as the driving source to drive the pick-up roller 201, the paper feeding roller 202 and the reverse roller 204; and a lift motor 220 as the driving source to drive the knock-up plate 131, respectively. However, the installation of two independent motors can increase the production cost significantly. Moreover, the double installation of the motors can also be bulky which tends to lower space efficiency of an image forming apparatus such as a multi-functional product. Accordingly, there is a need to provide a paper feeding apparatus for use in an image forming apparatus which advantageously utilizes a single driving source to drive both a knock-up plate and a paper feeding roller assembly at the same time so as to reduce production costs and promote internal space efficiency.